Farming the Seas — Issues
Farm raised fish and seafood are often stocked in high densities to maximize profit, which increases stress on the animals and the potential for developing disease. Antibiotic use to combat disease, once in heavy use in the developed world, has dramatically declined due to development of vaccines and selective breeding. In developing countries such as Thailand, the world's largest producer of farmed shrimp, however, antibiotic use is prevalent. Many scientists have concerns about the danger of creating resistant pathogens with the use of these antibiotics, especially when medications used to treat animals are the same as the ones used for humans. Industry representatives note that antibiotic use in aquaculture is lower than in poultry or beef feedlots, but others feel the use of these chemicals in an aquatic environment can be more risky. Industry and governments have made some attempt to inform farmers of the dangers of unwise antibiotic use and even pass regulations, but lax enforcement and the dire need to try and salvage harvests contribute to continuing use. Many antibiotics are readily available and unlabeled, sold as "miracle" products for controlling diseases. In 2003, the Aquaculture Certification Council, created by the shrimp industry trade association (Global Aquaculture Alliance) began certifying shrimp farming operations in developing countries. Most conservation groups do not consider this initiative as an in dependent, 3rd party effort, thus raising questions about the credibility of the program for creating a meaningful label for consumers. [back to top]
Aquaculture & Sustainable Aquaculture
Aquaculture: With a growing world population and marine fisheries in decline, fisheries experts have long hoped that aquaculture might one day take up the slack. In some ways it already is, but a growing number of marine scientists believe that parts of the industry may instead contribute to the further decline of marine resources. The intense controversy pertains to which species are being farmed and how they are being farmed. Salmon, shrimp and tuna are examples of carnivorous animals that must be fed other fish. Most farms raising these species ultimately consume more fish than they produce. The profit motive also inclines many farms to implement large-scale, industrial practices that can result in pollution, the destruction of marine habitat, and a tendency to generate diseases that pose a risk to both wild fish and consumers.
Sustainable Aquaculture: In order to be truly sustainable, aquaculture operations need to operate in ways that do not harm marine ecosystems or coastal communities; that neither consume more resources than they produce or rob future generations of a healthy ocean. In China, millions of people depend on farms that raise carp, an herbivorous fish that requires no fishmeal. Carp are omnivorous species like catfish and tilapia that can be farmed with very little need of fishmeal or fish oil. Farms that raise shellfish like abalone, clams, oysters and mussels also produce a net gain in protein for a hungry world. These kinds of aquaculture are best suited for truly taking pressure off our over-exploited oceans. [back to top]
Wild salmon develop their robust color naturally by feeding on prey such as krill (tiny shrimp-like crustaceans), which contain a chemical compound called astaxanthin. Farmed salmon are fed with formulated feed pellets that contain either synthetically produced or naturally derived chemical colorants that are designed to give the flesh of farmed fish a look similar to the wild salmon. If colorants weren't used, the flesh of most farmed salmon would be more of a gray hue. According to a 1997 study, a chemical commonly used to color farmed salmon called canthaxanthin was linked to temporary blind spots and possible damage to the retina, but a person would have to eat 24 lbs of farmed salmon a day for several weeks to reach dangerous levels. Astathanxin and canthaxanthin are both antioxidants that are essential to fish health. A class-action lawsuit in 2003 led to a mandatory label requirement differentiating artificially colored farmed salmon from wild salmon in grocery stores. [back to top]
The way most of the world's marine fisheries and aquaculture industries operate has less to do with effective management regimes than with pressures brought to bear by a globalized world market. Most fish products consumed in the US, Japan and Europe are produced in developing nations that lack resources for enforcing regulations. As long as there is strong demand for a product, even if it results in the destruction of marine ecosystems, the market often provides it. Thus, the way most seafood products are produced is ultimately driven by consumer demand while most consumers and retail vendors remain unaware of where their seafood comes from. Many are confused as to whether farm-raised seafood is a good idea or not. Most of us are equally unaware of our own powerful influence each time we make a decision on which products to buy or not to buy. Each time we "vote with our pocketbooks, " it sends a very clear signal to producers. Just as consumer demand for pesticide-free fruit and vegetables created an immense boom in organic agriculture, the demand for environment-friendly seafood is changing the way seafood is produced. Buy a product from a sustainable fishery and you encourage positive change. [back to top]
Diminishing Fish Stocks
According to the most comprehensive and recent data published by the United Nations, two-thirds of the major marine fisheries of the world are currently fully exploited, over-exploited, or depleted, compared to just five percent reported 40 years ago. Fishermen, seafood merchants, and marine scientists have reported an alarming decline in ocean fish populations. The total world catch peaked in 1989 at about 100 million metric tons per year. Despite a continuing increase in the number and capacity of fishing vessels, the world catch has likely declined ever since. A recent study by Ransom Myers revealed that only 10% of larger species like tuna and swordfish still remain in the world's oceans since the advent of modern, high-tech fishing practices. [back to top]
Disease and Parasite Transfer
Are farmed fish in danger of picking up diseases and parasites from wild fish or is it the other way around?
Disease: Diseases such as infectious salmon anemia and white spot virus (shrimp) may originate in the wild, but they tend to be greatly amplified within the confines of a crowded net cage or pond. High stocking densities on farms create crowded conditions that stress animals and make them more susceptible to viral and bacterial diseases. The diseases spread very rapidly inside the farms and have greater potential to infect wild fish and other marine life outside the farm. Over the past 10 years, aquaculture operations in the developed world have implemented vaccines to control many diseases and to reduce the use of antibiotics. There are not yet vaccines for all diseases, and in developing nations, antibiotic use remains rampant and largely unregulated (see antibiotics).
Parasites: Infestations of sea lice also plague the salmon farming industry. Fish farmers say that farmed salmon pick up sea lice from the wild. Critics acknowledge this, but point out that, as with disease, the high stocking densities tend to magnify and spread the problem. The farms can then contribute to epidemics of sea lice in wild populations, particularly where pens are sited along migratory routes of wild salmon, which many are. Sea lice infestations remain a major threat to both farmed and wild fish in many areas where salmon is farmed. [back to top]
Most of the world's shrimp farms are in developing countries like Thailand, where farms often drain effluent from their ponds directly into local estuaries and near-shore waters. This effluent often contains bacteria, viruses, excessive nutrient loads and chemical disinfectants. There are laws against this kind of pollution, but developing nations are often unable to enforce them. With salmon aquaculture, the majority of open-net farms are located in near-shore waters along coastlines that are also major migratory routes for wild salmon. Undigested food, excrement and other wastes can accumulate beneath the pens, which can lead to pollution, algal blooms, and a breeding ground for various pathogens. In recent years many salmon farms have been sited or re-sited in areas with more tidal surge. [back to top]
Over one million farmed salmon have escaped their net cages over the last ten years in British Columbia and Washington, often as the result of storm damage or human error. Most of these farmed fish are Atlantic salmon, a different species than Pacific. There are concerns that the escaped fish compete with wild Pacific salmon and may even have the potential to displace populations that are struggling to survive. In Atlantic waters (Norway, Maine and Scotland), the escaped fish can also interbreed with wild Atlantic salmon populations, effectively diluting the wild gene pool, making them less fit for survival. In recent years the industry has rebuilt many net cages with more durable materials to help reduce the risk of escapes. Critics of the industry believe salmon farms should be taken completely out of the ocean and moved into land-based tanks to eliminate any risk of escape and the transfer of disease. Land-based tanks, however, are expensive and may not yet be commercially viable. [back to top]
Fishmeal as Feed
Carnivores or herbivores? In one sense, it can be said there are generally two types of aquaculture: operations that raise carnivorous fish (species higher on the marine food chain that require fish flesh and fish oil in their diets), and those that raise herbivorous or omnivorous species that require mostly or wholly plant-based feeds. This second broad category also includes farms raising shellfish, the filter-feeding mollusks and bivalves that obtain the nutrients they need from seawater. Part of the intense debate over aquaculture centers around the immense volume of fish that must be caught in the ocean to feed farm-raised carnivorous species.
Debate over Fishmeal Pellets: Most farm-raised carnivorous species like shrimp, salmon, cod, and halibut are fed formulated feed pellets comprised of grain, dried fishmeal and fish oil. Most fishmeal and fish oil is manufactured from anchovies, sardines, capelin, and sand eels, and the fisheries that target these species are considered by some fisheries experts to be well-managed. Not all fishmeal is sourced this way. In Thailand, most shrimp farmers buy less expensive fishmeal that is produced from marine life captured by bottom trawls, a type of fishing gear notorious for high levels of bycatch, which can also destroy seafloor habitat. There is a range of scientific opinion about exact conversion ratios, but most fisheries experts agree that these kinds of aquaculture consume more fish than they produce, putting added pressure on ocean fish populations.
Bluefin Tuna: Perhaps the most extreme example of a lop-sided conversion ratio is the "ranching" of bluefin tuna, in which wild tuna are captured and put into netcages where they are fattened up for the lucrative sushi market. During the 4-6 month fattening period, they consume up to 17 pounds of fish for each pound of weight gained. Tuna ranchers (see interview transcript for Gines Mendez) say that the great volumes of fish daily dumped into the cages would also be consumed by the tuna in the wild, thus suggesting there is no real loss of marine resources. But critics of the industry point out that the industrial capture of forage fish like anchovies and mackerel effectively remove great volumes of these species in very concentrated areas, whereas wild tuna tend to forage for a greater variety of species over vast areas, with no risk of destabilizing marine ecosystems. They also point out that significant volumes of bycatch are involved with most industrial fishing practices.
Fishmeal and Fish Oil: If the industrial sector farming carnivorous fish species continues to grow at current rates, the United Nation's FAO reports that the fish populations being targeted for fishmeal could be dessimated within a decade. (see interview transcript for Ulf Wijkstrom)
Some scientists working with the aquaculture industry argue that raising carnivores has not increased the total volume of fish being officially targeted for fishmeal and oil, which is also used to feed swine and poultry (see interview transcript for Ron Hardy). However they acknowledge that the portion being used for aquafeeds is steadily growing, and at the current growth rate, the aquaculture industry will require volumes in excess of what the oceans can sustain.
There is a potential for substituting grains for fishmeal and vegetable oils for fish oil, although this replacement affects the flavor and physical quality of the meat, and could reduce the content of healthy omega-3 fats. The industry is experimenting with adding marine algaes and plankton to replace omega 3s. [back to top]
Some wild and farm-raised seafood products are known to have dangerous levels of toxins like mercury, PCBs (polychlorinated biphenyls) and dioxins. PCBs are considered probable carcinogens and have been banned in the U.S. since the late 1970s. Dioxins are known to cause cancer. The contaminants being found in both wild and farmed fish are due to the fact that our oceans are becoming increasingly polluted from land-based run-off and atmospheric pollutants. The toxins tend to bio-accumulate at increased levels in the tissues of fish higher in the food chain (fish that prey on other fish). Tuna and swordfish are examples of wild fish that are accumulating toxins at highest levels.
Farmed fish that are fed fishmeal and fish oil also tend to accumulate higher levels of PCBs and dioxins. Farmed salmon are known to have 10 times the amount of PCBs and dioxins (carcinogens) than wild salmon, largely because wild salmon tend to naturally eat lower on the marine food chain, consuming more krill and shrimp. The farming of fish like tuna may present an even bigger health risk, because they are fed much greater volumes of forage fish.
According to the salmon farming industry, the levels of PCBs in their products are safe for consumption because they remain below the FDA standard of 2 parts per million. But according to a growing number of scientists, the FDA standard is outdated and not solely based on health considerations. They believe that the EPA standard, a much more rigorous index, is more accurate measure of what are safe levels for these dangerous toxins.
The largest international study on farmed salmon to date, published in Science Magazine Jan. 9, 2004, found that following the EPA standard, farmed salmon from supermarkets in Frankfurt, Edinburgh, Paris, London, Oslo, Boston, San Francisco, and Toronto triggered consumption recommendations of one-half to one meal of salmon per month. In Los Angeles, New York, Washington, D.C., Seattle, Chicago, Denver, New Orleans and Vancouver, recommended consumption rates of farmed salmon landed at no more than two meals per month. Nearly across the board, the farmed salmon samples tested significantly exceeded the containment levels of wild salmon, which could be consumed at levels as high as eight meals per month.
The Difference between FDA Standards and EPA Standards
FDA Standard: Congress originally mandated the FDA to set levels for regulating toxins for the interstate transport of foods. These levels were set to consider health effects, but also to reflect considerations of economic impact on industry. The standard for PCBs has not been updated since 1984. Critics say the FDA standards focus too much on the economic implications of restrictions and not enough on the long-term health effects of PCBs and dioxins which build up in body fat and linger there for decades.
EPA Standard: The EPA standard, in contrast, is based solely on consideration of what is known for the health effects of the contaminants in food and it's based on more current information. For PCBs, the EPA says it's safe to eat an unlimited number of fish if the PCB level is 0.05 parts per million, a 40-fold lower value than levels set by the FDA. EPA guidelines say that if a person eats fish twice a week, it should contain no more than 4 to 6 parts per billion of PCBs. The most recent and extensive study on toxin levels in salmon found that PCB levels in farmed salmon sold in the United States and Canada averaged about five times that amount: 30 parts per billion (see Dr. David O. Carpenter's transcript on this website).
A summary the study, originally published in Science (January 2004) is available from the EPA here.
Over half of the world's population is concentrated in coastal areas. In the developing world, coastal communities depend on marine resources and centuries-old, sustainable fishing methods to make ends meet. There are concerns that some forms of industrial, intensive aquaculture may result in short-term profit, but can also result in a loss of marine resources and traditional food production-both agriculture and sustainable artisinal fisheries. In some areas where intensive operations have been located, nearby estuaries and inter-tidal zones have been negatively impacted. These areas are vital breeding and nursery habitats for many species of fish and shellfish. Another factor to consider is that shrimp farming in developing countries is almost entirely for export. Industry spokespersons point to a better standard of living, but critics see this form of aquaculture as an extractive, exploitive industry where resources that could feed local people are diverted into a global market benefiting a small fraction of the world's (more affluent) human population. [back to top]
Globalized World Fish Market
With the advent of jet cargo and modern refrigeration, fish (fresh and frozen) have become a globally traded commodity. Most metropolitan airports have special on-site refrigeration facilities designed for seafood. In the large wholesale fish markets, it is common to see fresh seafood products flown in from half-way around the world that were caught or harvested within the previous 48 hours. In Tokyo's Tsukiji fish market alone, over six million pounds of fish and shellfish are sold every day, and most of this seafood is imported. The U.S. and Europe are also net importers, often from areas where effective fishery management plans do not exist. [back to top]
Impacts on Surrounding Communities
Aquaculture, or the "blue revolution" as it's called, is changing the face of coastal communities around the globe. In Thailand we met shrimp farmers who say they can make a lot more money by growing shrimp than rice. We met others who have gone bankrupt after losing consecutive 'crops' to disease. Critics say that local communities do not generally benefit; the shrimp are exported, the workers are usually hired from outside the community, and the income made by urban investors does not "trickle down" to local people. Spokespersons for the industry point out that the processing centers that prepare farmed shrimp for export do tend to hire local people and often contribute to local infrastructure. The proliferation of salmon farms in western Scotland and British Columbia has also been a mixed blessing for coastal communities. The industry has created jobs in some economically depressed areas, but commercial fishermen have concerns that pollution and disease associated with these farms have a negative impact on wild fisheries, putting many more jobs at risk. [back to top]
Offshore Fish Farms of the Future
The National Marine Fisheries Service is considering the possibility of leasing offshore waters in the Atlantic and Pacific to various kinds of aquaculture ventures-operations that involve complexes of submerged netpens anchored to the seafloor. The large companies advocating for these leases envision this type of aquaculture as the wave of the future for growing species like cod, tuna and halibut. Many marine scientists believe that such ventures should not begin without an opportunity for public debate or sufficient precaution taken to avoid many of the same problems associated with nearshore aquaculture, such as disease transfer, the escape of domesticated breeds, and the consumption of wild fish as feed. There are also concerns about the privatization of continental shelf areas that have always been in the public domain. [back to top]
In evolutionary time, the large-scale changes taking place in the ocean are very sudden. Exponential growth of the world's human population is part of what drives overfishing and the rapidly expanding aquaculture industry. 2/3 of the world's six billion human inhabitants live within 40 miles of an ocean and these coastal areas include many of the largest cities. With the total world population projected to reach 9 billion by 2050, an additional 40 million people are being added to these areas each year. Over one billion people in Asia already depend on ocean fish for their protein, as do one of every five Africans. Per-capita seafood consumption in the U.S. and Europe is higher than in many developing countries, and the FAO predicts that over the next 25 years per capita consumption in North America and Europe will increase 64% and 83% from 1995 levels, respectively. [back to top]
Pressure on Wild Stocks
Although it has long been hoped that farming the seas might be the "silver bullet" that can help relieve excessive fishing pressure, most fisheries experts now agree that aquaculture alone will not solve the problem. Effective management of capture fisheries is as essential as the development of truly sustainable aquaculture practices. Both must become a reality to avoid massive problems. Examples of sustainable aquaculture include the cultivation of herbivorous fish and filter-feeding shellfish-industries that provide a net gain in fish protein for millions of people without bringing additional fishing pressure on wild stocks. Other pressures that some forms of aquaculture have brought to bear on wild fish include pollution, disease transfer, the introduction of invasive species (escaped fish) and the destruction of marine habitat. [back to top]
Genetically modified (GM) salmon are already being marketed that have been engineered to grow to market size in half the time of ordinary Atlantic salmon. These fish are also known to be less fit for survival in the wild. Although not yet sanctioned for use in US waters, industry insiders predict that GM fish will be grown in Chilean waters within the next 2 years. In order to compete, salmon growers around the world may be inclined to follow. Many scientists believe the potential ramifications of raising GM fish are too unstudied to risk their escape into the natural environment where they have the potential to mix their altered genes with wild populations. Over one million farmed fish have escaped their net cages in the Pacific Northwest over the last 10 years (see Escapes). Although GM salmon are engineered to be 99% sterile, if 100,000 fish escape, 1000 of those altered (genetically inferior) fish might be able to reproduce. There have also been no long term studies on the human health effects of consuming GM salmon. [back to top]
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